previously experimentally determined as concentration of Ca2+ for 1/2 phi

n

Hill coeff, measure of coopertivity

also need to define “alpha” as scaling term and “beta” as non-specific term to solve for phi in terms of Kd, [Ca2+] and n

results

single stimuli (pg 9574)

“In response to a single action potential, the synthetic indicator produced robust, rapid onset fluorescence changes….In contrast, [two GECI] produced only very small fluorescence responses; these were detected above the noise only when averaging over many (8-16) trials.”

Fig 2A

variable patterns of stimuli (pg 9575)

“both [chemical indicators] respond to Ca2+ elevations sufficiently quickly to follow the stimulus patterns reliably. In contrast, GECI power spectra did not reveal a clear peak above the noise at the stimulus frequency , even under the most favorable conditions. Thus, unlike synthetic indicators, GECIs respond too slowly to follow individual action potentials within a burst.”

Fig 3

as quantitative measure of Ca2+ (pg 9575)

“GECIs have idiosyncratic and complex fluorescence saturation curves, making their use for quantitative [Ca2+] imaging problematic.”

Fig 5

interaction of GECI with CaM-binding proteins in cell (pg 9576)

“Because CaM (and hence GECI) properties are changed by interactions with CaM-binding proteins, assessing GECI mobility is important for the interpretation of GECI signals”

“In all cases, after bleaching, fluorescence recovered to >95% of the baseline fluorescence.”